Organisms living in water include organisms that adhere to underwater structures and cause various damages. For example, barnacles, mussels, and hydrozoans sometimes grow adhering to ships. In such cases, damages such as ship speed reduction and fuel consumption increase may be caused. As countermeasures against these problems, paints capable of reducing adhesion of the above-described organisms are applied to ship hulls. There are known active components of the paints, such as cuprous oxide and copper rhodanide.